The worst though is when you just buy something only to find it reduced or free a day later or something. That happened to several people with Shadow Warrior. It went F2P recently on Steam and people were bawling about how they'd just bought it and wanted a refund -- and these were people who had bought it on GOG, and not Steam.
I went over to GOG just now and got this. I'll download it later on my other PC. For me there's nothing better than free games like this. GOG rules.